Plate-gripping mechanism for offset printing cylinder



1965 J. D. KEELER 3,202,098

PLATE-GRIFFING MECHANISM FOR OFFSET PRINTING CYLINDER Filed March 5, 1962 2 Sheets-Sheet l JHCK D. KEELER AT'TO RNEVS INVENTOR.

1965 J. D. KEELIER 3,202,098

PLATE-GRIFFING MECHANISM FOR OFFSET PRINTING CYLINDER Filed March 5, 1962 2 Sheets-Sheet 2 FIG.2

INVENTOR. JFK/ D. KEELER s 44 @M GM ATTORNEY5 United States Patent 3,2ti2,ti% PLATE GRllPif-IG li i'EQZ lANidll/l Ffllt. @FFEEET PlitlhlflN-G CYLHNDER .laclt Keeler, Seattle, Wash, assignor to Norliu, Inn, Seattle, Wash, a corporation of Washington Filed I i liar. 5, 1962, Ser. No. 177,263 12 Claims. (til. 1tildl5.1)

This invention relates to a plate-gripping mechanism for use with an offset printing cylinder so as to attach to the cylinder the master sheet, or plate as it will be hereinafter termed, on which the material which is to be printed has been aflixed.

It is the principal object of the invention to provide a device of perfected design by which the plate may be easily and quickly gripped and one, especially, which is automatic in the sense that it is unnecessary for the operator to manipulate any part of the device in order for the gripping function to be performed, hence permitting the operator to employ both hands in feeding the plate to the gripping device.

As a further important object the invention aims to provide plate-gripping mechanism which is self-energizing to the extent that the security of the grip increases with increasing pull upon the gripped plate.

A yet additional object of the invention is to provide a mechanism of the above character which permits a gripped plate to be released at will with ease and expedition.

The invention further ain s to provide a plate-gripping mechanism in which the gripping oflice is performed without marring or otherwise injuring the gripped plate.

The invention has the yet further and important object of providing a plate-gripping mechanism which permits one plate to be gripped and another blanking over-lay plate later applied and gripped by the mechanism in a position covering a portion of the first plate without necessitating release of the grip upon said first plate.

Other objects and advantages looking to the provision of a perfected plate-gripping mechanism of comparatively simple and inexpensive construction which will reliably perform the function for which it is intended will, with the foregoing, appear and be understood in the course of the following description and claims, the invention consisting in the novel construction and in the adaptation and combination of parts hereinafter described and claimed.

In the accompanying drawings:

FIGURE 1 is a fragmentary transverse vertical sectional view illustrating an offset printing cylinder of a type to which the present invention lends itself, and showing mounted thereon a plate-grip constructed in accordance with the preferred teachings of the present invention.

FIG. 2 is a fragmentary front elevational view of the grip mechanism shown detached from the cylinder.

FIG. 3 is a fragmentary horizontal sectional view on line E' 3 of P16. 4, employing the same scale as that of PEG. 1 and 2. i FIG. 4 is a transverse vertical sectional view drawn to an enlarged scale on line of PEG. 2 and incorporating a phantom illustration of a fragmentary portion of the cylinder together with a broken-line illustration of the position into which fingers which grip the plate are moved for releasing the plate.

FIG. 5 is a transverse vertical sectional view drawn to an enlarged scale on line 5-5 of FIG. 2, with parts broken away, and embodying a gripping finger of modi- .3,2Z'Z,@% Patented Aug. 2 1965 view drawn to a scale considerably larger than FIGS. 4', 5 and 6 on line 7--7 of FIG. 2, and incorporating a fragmentary showing of the cylinder with a plate gripped thereto in position for printing.

' Referring to said drawings, the numeral 3 designates an otfest printing cylinder of a type to which the present invention lends itself. In such cylinder there is provided a surface ill for the master plate which is developed concentric to the rotary axis of the cylinder through somewhat less than a full circle. A ledge 11 on which the plate-gripping device of the present invention is mounted lies at one end of said concentric surface 10 and extends substantially the full length of the cylinder. A recessed groove 12 extends longitudinally of the ledge on the approximate median line thereof.

According to the present invention a mounting block is removably secured upon the ledge by bolts 13. As can be best seen from an. inspection of FIG. 5, the pro file configuration of the block as viewed from an end is one providing a mounting base denoted generally by lid crowned along the front by a cornice-like perch 15. The perch is given a moderate overhang and from the after edge of the produced chin surface to a front face 17 slopes rearwardly at a rathersteep angle. At the substantial juncture of this sloping face 1'? and the hori zontal bottom face 18 of the base there is provided an open-bottom ,re-entrant vertical slot 20. The top of the block is stepped so that the upper face 21 of the perch occupies a level above the upper face 22 of the base, with the rearwardly facing riser surface 23 which lies between said surfaces 21 and 22; being located, by preference, somewhat to the front of the longitudinal vertical plane occupied by the slot Zil. At moderately close intervals of the length, the block has relatively deep open-front slots 24 cut therein on paralleling transverse vertical planes.

A plurality of bell-crank levers 25, one for each of said several slots 24, are strung upon a pivot rod 26 and such rod seats in a mating groove 2'7 cut in the perch along its underside l6. Cap screws 28 (see FIGS. 2, 3 and 4) bear upon the rod to removably hold the same in the groove. Form said fulcrum 2'5 one arm 3t) of each bell-crank lever depends to a level coinciding with that occupied by the bottom face of the mounting base. The fore-and-aft breadth of this arm 3b is substantially less than the depth of the slots 24 so that the arm can swing inwardly about the fulcrum. The other arm 31 of the respective levers extends horizontally inwardly above the top face of the mounting base.

An L-shaped lever-forming plate 32 has one of its wings, designated by 33, bearing upon the top face of the mounting base in a position underlying said several lever arms Fill, and is yieldingly pressed against said face by two or more spring-thrust washers 34. Posts 35 which carry the springs 36 are threaded into the mounting base. The other wing 37 of the plate 32 rises from the rear edge of the wing. The wing 37' is adapted to be pressed by hand in a rearward direction against the yielding restraint of the springs 36. Wing 33, being tilted upwardly about said rear edge as a rocker fulcrum in response to said rearward movement of the wing 37, lifts the horizontal arms 31 of the bell-crank levers to responsively swing the hanging lever arms 353! in an inward direction. In a manner which will be apparent as the description proceeds, said inward motion of the hanging lever arms releases a plate s gripped by the hanging arms. The plate is shown in MG. 7.

The mounting base has a transverse groove 40 (FIGS. 2 and 6) routed from its top face at a point central or approximately central to the length, and a prolongation of this groove extends as an undercut forwardly beyond the riser face 23. A flange 41 formed uponthe lower end of a knurled nut i2 is arranged to be caught in said undercutting prolongation, with its function that of preventing endwise motion of the nut. The bolt complement d3 of the nut 42 is soldered or otherwise made integral with a bar 44 extending substantially the full length of the block and received for vertical slide motion Within the re-entrant longitudinal slot 242.

When bolted to the ledge 11, the block is so located that the bar 44, when lowered, will project into recess 12 and lie against the front face thereof. The operator inserts the upper end x of said master plate s inwardly over the top edge of the ledge 11. Such plate end can Work freely under the arms 39 of the bell-crank levers in that rearward swing of these arms is opposed only by the nominal gravitational resistance which the horizontal arm 31 of each lever imposes. These levers are light in weight, being stamped from thin metal of, say, in thickness. The plate end x thereupon becomes locked against retraction. From the fact that a plane perpendicular to the ledge and traversing the fulcrum of the levers is spaced forwardly beyond the outer limit of the ledge, a wedge action occurs by said gravitational force of the lever arms 31 augmented by any pull to which the plate is subjected, exerting a powerful clamping force upon the plate. Disengagement is, however, readily and easily accomplished simply by pressing the wing section 37 of the lever-forming plate 32 rearwardly to rock the same about its rear edge as a fulcrum and thereby back off the gripping ends of the lever arms 30, whereupon the plate end may be freely withdrawn from the gripping throat. It is to be noted that the two hands of an operator are free to hold both sides of the plate when inserting the same into the gripping throat in that it is not necessary to press upon the releasing lever to cause the lever arms 3% to swing rearwardly. The clamping action is perforce self-energizing.

In FIG. I have shown a modified form of bell-crank lever 125 which is designed in a manner which employs the load of the springs 36 as a positive force yieldingly urging the vertical arms 13% of the levers into their plategripping position. In this modified lever there is provided a re-entrant slot 138, located at the juncture of the arms 13$] and 131, into which the free tip of the wing 33 extends. As the springs 36 press said wing 33 downwardly said tip, by reason of its bearing engagement against the lower wall of the slot 138, forces the vertical lever arms 130 outwardly.

Reverting now to the stop bar 44, the same has as its function to prescribe one limit to which the grip end x of the plate may be inserted, and may be raised at will into an out-of-the position, whereupon the plate may be advanced to a greater degree, working into the groove 12.

The provision of a multiple plate-gripping fingers (the lever arms 30), with each being movable independently of the others, is significant in that this permits a master plate to be first clamped to the cylinder and, if desired, a portion or all of one side thereof blanked ofi by a later-inserted over-lay sheet. The insertion of said over-lay or blanking sheet under several said fingers in no way modifies the clamping action which the other fingers continue to impose upon the master plate, wherefor there is no liability of disturbing the position of the master plate in consequence of the application of the blanking sheet.

It is believed that the advantages of the invention will have been clearly understood from the foregoing detailed description of the illustrated preferred embodiments. Minor changes will suggest themselves and may be resorted to without departing from the spirit of the invention, wherefor it is my intention that no limitations be implied and that the hereto annexed claims be given a scope fully commensurate with the broadest interpretation to which the employed language admits.

What I claim is:

1. An offset printing cylinder having within its circumference a longitudinally extending re-entrant opening defining a pocket one wall of which provides a grip ping surface disposed in angular relation to the perimeter of the cylinde gripping means mounted in said pocket for movement both inwardly and outwardly relative thereto and in said movement guided directively from and directively toward said gripping surface as the gripping means moves inwardly and outwardly, respectively, and by said guided outward motion operating by wedge action to grip an inserted end edge of a plate between the gripping means and said gripping surface, said gripping means comprising a plurality of independently acting elements spaced apart at intervals of the length of the pocket, and a manually activated means common to said several elements for moving the latter in concert for moving the gripping means in an inward direction for releasing the plate, means being provided establishing an interconnection between the several fingers during said inward and outward movements.

2. In combination with an oifest printing cylinder having a re-entrant opening forming a planar ledge lying angular to the perimeter of the cylinder, mechanism for gripping an end edge of a plate inserted in said opening comprising: a mounting block secured in surmounting relation upon said ledge and with an outer portion of said planar ledge producing a pocket of extended length open to the front, gripping means comprising a plurality of fingers spaced apart at intervals of the length of the pocket and pivoted from the block to swing about a common axis spaced above the ledge in a plane raised perpendicular to the plane of the ledge from a point spaced outwardly beyond the outer limit of the ledge and being thus caused to progressively approach toward said outer portion of the ledge in the outward motion of the fingers and progressively recede from said outer portion in the inward motion of the fingers, pressure means yieldingly urging said gripping fingers out wardly toward the open mouth of the pocket, and means subject to manual operation for retracting said gripping fingers against the force exerted by said pressure means, the plate being gripped by inserting an end edge thereof between the gripping fingers and the ledge.

3. Structure according to claim 2 having stop means limiting the distance to which said end edge of the plate may be inserted.

4. Structure according to claim 2, the block providing an open groove for the seating engagement of a pivot pin on which the fingers are strung, means being provided releasably holding the pivot pin in said groove.

5. Structure according to claim 2, the block providing open-front slots guiding the fingers for swing motion in established vertical planes transverse to the pocket.

6. Structure according to claim 2 in which the gripping fingers are formed as one of the two arms of respective bell-crank levers, the other arms of said levers extending horizontally inwardly from the pivot axis, the force of light intensity which yieldingly urges the gripping fingers outwardly toward the open mouth of the pocket being imposed upon said last-named arms.

7. Structure according to claim 6 in which the retracting means comprises an L-shaped plate fulcrumed upon the mounting block to rock about the juncture of its two wings as an axis and having one of said wings extending outwardly from the fulcrum in a position underlying said horizontal arms of the bell-crank levers and its other wing rising from said fulcrum so as to be pressed rearwardly by hand, means being provided yieldingly resisting said rearward hand pressure.

8. in combination with an offset printing cylinder having a re-entrant opening forming a planar ledge lying angular to the perimeter of the cylinder, mechanism for gripping an end edge of a plate inserted in said opening comprising: a mounting block secured in surmounting azoaoes relation upon said ledge and in conjunction with an outer portion of said planar ledge producing a pocket of extended length open to the front, a plurality of fingers spaced apart at intervals of the length of the pocket and so pivoted from the block about a common axis spaced above the ledge as to swing inwardly and outwardly relative to the pocket and by said outward movements produce a wedge action to grip an inserted end edge of a plate between the free ends of the fingers and the surface of the ledge, said fingers being formed as one of the two arms of respective bell-crank levers having their other arms extending horizontally inwardly from the pivot axis, and means for lifting said horizontal arms so as to swing the fingers inwardly for releasing the plate.

9. Structure according to claim 8 in which the retracting means comprises an L-shaped plate fulcrumed upon the mounting block to rock about the juncture of its two wings as an axis and having one of said wings extending outwardly from the fulcrum in a position underlying said horizontal arms of the bell-crank levers and its other wing rising from said fulcrum so as to be pressed rearwardly by hand, means being provided yieldingly resisting said rearward hand pressure.

10. Structure according to claim 8 in which the block provides open-front slots guiding the fingers for swing motion in established vertical planes lying transverse to the pocket.

11. Structure according to claim 8, the block providing an open groove for the seating engagement of a pivot pin on which the fingers are strung, means being provided releasably holding the pivot pin in said groove.

12. An offset printing cylinder having within its circumference a longitudinally extending re-entrant opening defining a pocket one wall of which provides a gripping surface disposed in angular relation to the perimeter of the cylinder, gripping means mounted in said pocket for movement both inwardly and outwardly relative thereto and in said movement guided directively from and directively toward said gripping surface as the gripping means moves inwardly and outwardly, respectively, and by said guided outward motion operating by Wedge action to grip an inserted end edge of a plate between the gripping means and said gripping surface, means subject to manual control for moving the gripping means inwardly for releasing the plate, and a means which is made inactive at will operating when active as a stop limiting the distance to which the end edge of the plate can be inserted.

References Cited by the Examiner UNITED STATES PATENTS 809,288 1/06 Dick 101-4151 1,168,498 1/16 Harrold 1014l5.1 2,386,214 10/45 Harrold et a1. l01-4l5.l 2,453,927 11/48 Morse 101-4151 2,730,949 l/56 Mitchell l0l415.1 2,990,772 7/61 Fischetti 10l-415.1

FOREIGN PATENTS 808,224 1/59 Great Britain.

EUGENE R. CAPOZIO, Primary Examiner. R. A. LEIGHEY, Examiner. 

1. AN OFFSET PRIINTING CYLINDER HAVING WITHIN ITS CIRCUMFERENCE A LONGITUDINALLY EXTENDING RE-ENTRANT OPENING DEFINING A POCKET ONE WALL OF WHICH PROVIDES A GRIPPING SURFACE DISPOSED IN ANGULAR RELATION TO THE PERIMETER OF THE CYLINDER, GRIPPING MEANS MOUNTED IN SAID POCKET FOR MOVEMENT BOTH INWARDLY AND OUTWARDLY RELATIVE THERETO AND IN SAID MOVEMENT GUIDED DIRECTLY FROM AND DIRECTIVELY TOWARD SAID GRIPPING SURFACE AS THE GRIPPING MEANS MOVES INWARDLY AND OUTWARDLY, RESPECTIVELY, AND BY SAID GUIDED OUTWARD MOTION OPERATING BY WEDGE ACTION TO GRIP AN INSERTED END EDGE OF A PLATE BETWEEN THE GRIPPING MEANS AND SAID GRIPPING SURFACE, SAID GRIPPING MEANS COMPRISING A PLURALITY OF INDEPENDENTLY ACTING ELEMENTS SPACED APART AT INTERVALS OF THE LENGTH OF THE POCKET, AND A MANUALLY ACTIVATED MEANS COMMON TO SAID SEVERAL ELEMENTS FOR MOVING THE LATTER IN CONCERT FOR MOVING THE GRIPPING MEANS IN AN INWARD DIRECTION FOR 